The present invention relates to a kit and a method for preparing autologous fibrin glue, and particularly to a sealed container ready to use being provided with a coagulation activator suitable for obtaining autologous fibrin glue.
The fibrin glue is known to be a haemoderivative largely used as a topical surgical adhesive or an haemostatic agent. Several kits are available on the market containing concentrated fibrinogen from donors, associated to a proteic activator of human or animal origin, such as thrombin or batroxobin, for obtaining eterologous fibrin glue.
Such known kits involve the use of material of human or animal origin, which. owing to its origin, could result in possible viral contamination and in serious risks for the receiver of the fibrin glue. In the past the authorities have been several times compelled to suspend from the trade or even to ban the haemoderivatives obtained by using material of human or animal origin. Furthermore, rejection cases are known from the literature resulting from the reimplant in the patients of fibrin produced by using human or animal proteins. Such cases are indeed due to the eterologous origin, with respect to the receiver organism, of the sealant protein being reimplanted or some of the components used for preparing it.
The autologous fibrin glue, i.e. obtained from the blood of the patient himself, is more reliable with respect to the rejection and/or infection risks. Several procedures have already been described for obtaining extemporary autologous fibrin glue, but no xe2x80x9cready to usexe2x80x9d kit is by now available on the market although some relevant references can be found in the patent literature.
For example U.S. Pat. No. 5,733,545 discloses a plasma-buffy coat concentrate to be combined with a fibrinogen activator to form a platelet glue wound sealant. The method disclosed in this patent allows to process blood of the patient for obtaining autologous fibrin glue, but it comprises the use of thrombin or batroxobin as fibrinogen activator. These activators are of human or animal nature and therefore still involve the risk o reject and/or viral infections for the patient.
U.S. Pat. No. 5,585,007 discloses a method and an apparatus for making concentrated plasma to be used as a tissue sealant. The method consists in separating plasma from whole blood and removing, water from said plasma by contacting it with a concentrator to provide concentrated plasma which can be thereafter coagulated with a solution containing, thrombin and calcium. The apparatus comprises a first centrifuge separator in a first chamber, a concentrator included in a second chamber communicating with the first chamber, and a second separator. The method disclosed in this prior art reference requires a long time for obtaining the plasma concentrate necessary for the subsequent preparation of autologous fibrin glue and the apparatus is expensive and not disposable.
The object of the present invention is therefore to provide a ready to use kit, allowing to rapidly obtain autologous fibrin glue and particularly not resulting in viral infections and/or rejection cases when used in surgery.
Such an object is achieved by using a coagulation activator, being neither of human nor of animal origin, but being an inorganic compound which therefore cannot be infected and does not result in rejection.
The xe2x80x9cready to usexe2x80x9d kit according to the present invention comprises a sealed container containing calcium chloride as coagulation activator, Calcium chloride activates the fibrin present in patient""s plasma when this is introduced into the sealed container.
The kit according to the present invention has the great advantage of allowing the preparation of autologous fibrin glue which may be used with no risk of viral infections or rejection cases. Another advantage of the kit according to the present invention is that it allows the preparation of autologous fibrin glue from patient""s plasma in a very short time and in the desired form of clots or membrane or spray. Still another advantage of the kit ready to use according to the present invention is to allow the autologous fibrin glue to be obtained at costs proportionally lower with respect to the known systems.
Further advantages of the kit according to the present invention will be evident to those skilled in the art from the following detailed description of some embodiments thereof.
As container suitable for the kit according to the present invention can be used for example a glass container for antibiotics as hereinafter described in Example 1. Also glass or plastic test-tubes may be used. The preferred volume of the container is from 5 to 15 ml. The test-tubes have preferably a diameter ranging from 12 to 16 mm and a height ranging from 75 to 100 mill. The container should be suitably thick in order to withstand the stresses resulting from the pressure difference between its inner space and the atmosphere when it is evacuated. Hemispherical or conical bottom tubes are preferably 0.7 mm thick, flat bottom tubes 1 mm thick. The plastic containers are preferably made of transparent acrylic resin, 0.2-0.8 mm thick, in order to ensure the vacuum keeping for at least 12 months after production. The plastic test-tubes, after the preparation, are preferably introduced into a tin-foil vacuum air-tight container having a heat-sealed inner polyethylene layer, in order to ensure a perfect air-tightness until the date of use.
It should be noted that the evacuation of containers or test-tubes is advisable, however not necessary for putting the present invention into practice.
The containers or test-tubes are sealed by rubber or silicon pierceable caps, being suitable to ensure the container to be perfectly air-tight and to allow the vacuum plugging after the introduction of the chemical components and before the steam sterilization step.
After the sealing, the containers may be sterilized under steam at 121xc2x0 C. for 30 minutes. The sterilization may be carried out also by irradiation with gamma rays.
As a fibrin stabilizer tranexamic acid can be used, but also pure and crystalline epsilon-amino-caproic acid is suitable to this purpose. The amount will be about 1 g when using a 25 ml container, suitable for a plasma amount of 20 ml. Sometimes it is not necessary to use a fibrin stabilizer.
As a coagulation activator solid CaCl2.2H2O is used in the kit according to the present invention. For example, 11.76 mg, of CaCl2.2H2O will be introduced in a 5 ml container, by using a precision dosimneter (maximum error: 1-2 mg), in order to prevent polluting foreign components to be introduced.
In case of a 15 ml container for a plasma amount of 12 ml, the solid dehydrated calcium chloride amount to be introduced will be as high as 35.28 mg, while the tranexamic acid amount will proportionally be as high as 300 mg of crystals.
In case of a 25 ml container for a plasma amount of 20 ml, the dehydrated calcium chloride amount to be introduced will be as high as 58.9 mg, while the tranexamic acid amount will proportionally be as high as 500 mg of crystals.
Besides the dehydrated form used in the Examples, the calcium chloride may be in any other suitable form available on the market, e.g. as CaCl2.6H2O. Also a solution of this salt can be used, as described in Example 1.